Poster Presentation The 43rd Lorne Conference on Protein Structure and Function 2018

Cell envelope biosynthetic pathways as targets for novel antimicrobial drug design against Burkholderia pseudomallei and Neisseria meningitidis  (#239)

Courtney M Sullivan 1 2 , Andrew Scott 3 , Charlene Kahler 2 , Mitali Sarkar-Tyson 2 , Alice Vrielink 1
  1. School of Molecular Sciences, University of Western Australia, Crawley, Western Australia, Australia
  2. Marshall Centre for Infectious Disease Research and Training , University of Western Australia , Crawley, Western Australia, Australia
  3. Dstl, Porton Down, Salisbury, Wiltshire, SP4 OJQ, United Kingdom

The bacterial cell envelope is the first line of defense against antibacterial agents and is the target of several existing antibiotics. Antimicrobial therapy against Gram-negative organisms such as Burkholderia pseudomallei and Neisseria meningitidis is hindered by both their dual layer cell envelope structure, and acquired resistance to previously effective antibiotics. Proteins responsible for synthesis and assembly of the cell envelope represent promising targets for development of novel antimicrobials as they may increase membrane permeability and impair bacterial viability [1]. Transposon mutagenesis of B. pseudomallei K96243 has identified of a number of put­atively essential proteins associated with cell envelope biosynthesis, outlined in Table 1 [2]. This project will investigate these proteins and their orthologues as potential drug targets in B. pseudomallei and N. meningitidis. Targets will be characterized through a combination of structural and molecular biology approaches. Pure recombinant protein of each target will be produced, facilitating both structural studies and inhibitor testing. In addition, unmarked deletion mutagenesis will verify target essentiality in each organism. Pure recombinant protein will be used to investigate inhibitor efficacy through binding studies and enzymatic testing. Crystallographic studies will be performed in order to better inform future structure-based drug design. Progress towards these aims will be presented.

 

Table 1. Function and cellular location of targets of interest.

Name

Function

Cellular Location

UppS

Synthesises the glycan lipid carrier Und-P which essential for peptidoglycan formation

Cytoplasm

LptD

One member of the multi protein Lpt complex which mediates transport and selective insertion of lipopolysaccharide into the external leaflet of the outer membrane

Outer Membrane

LspA

Cleaves the signal peptides of prolipoproteins, an essential step towards formation of mature lipoproteins

Inner Membrane

ArnC

One enzyme within the ArnBCADTEF operon encoding for L-Ara4N synthesis and its transfer to Lipid A, resulting in resistance to cationic antimicrobial peptides

Inner Membrane
  1. [1] Bojkovic J, Richie DL, Six DA, Rath CM, Sawyer WS, Hu Q, Dean CR (2015) “Characterisation of an Acinetobacter baumannii lptD deletion strain: Permeability defects and response to inhibition of lipopolysaccharide and fatty acid biosynthesis”, Journal of Bacteriology, 198:731-741.
  2. [2] Dstl, unpublished